1. Field of the Invention
The present invention relates to an Internet protocol (IP) telephony system, and more particularly to a method for initializing an Internet protocol (IP) terminal.
2. Description of the Related Art
Firstly, prior to the explanation of the preferred embodiment of the present invention, the abbreviations and technical terms are defined as follows:
G/K:GatekeeperIP:Internet ProtocolVoIP:Voice over IPTFTP:Trivial File Transfer ProtocolDHCP:Dynamic Host Configuration ProtocolAAA:Authentication, Authorization and AccountMCU:Multi-point Control UnitRRG:Registration RequestRCF:Registration ConfirmationRAS:Registration/Admission/Status(Registration and Admission Control Signaling)RRJ:Registration Rejection
In recent times, following the current trend of rapidly growing Internet technology, an IP-based network or a packet-based network (hereinafter referred to as “IP network”) is developing rapidly not only in the Internet performance aspect but also in the Internet service aspect. For instance, the IP network is typically implemented in consideration of data transmission, but currently needs to be implemented in consideration of voice transmission as well as the data transmission.
According to demand for data and voice transmission at the same time, the IP network has been developed in the form of a multimedia service by which not only voice transmission, like a typical network, but also video and data transmission are possible. The IP network is called “VoIP (Voice over IP) system” or “Internet Protocol Telephony System” in that it makes it possible to perform voice communication between many subscribers by transmitting voice signals to them. Likewise, besides the data transmission, the voice transmission over the IP network is very important in the IP network. Under this condition, many developers are intensively conducting research into a voice transmission method in the IP network.
For example, a multimedia communication standard H.323 protocol recommended by ITU-T (International Telecommunication Union—Telecommunication) provides fundamental principles for voice, video, and data communications over the IP network including the Internet. One of the H.323 entities defined in the H.323 protocol is a gatekeeper. The gatekeeper binds H.323 endpoints present in a packet-based network (i.e., an IP-based network) in one control zone defined as a “Zone”, and then controls/manages the bound H.323 endpoints. For instance, there are a variety of H.323 endpoints such as a gateway, a terminal, and a MCU (Multi-point Control Unit). One gatekeeper is present in the zone, and is composed of at least one H.323 endpoint. A plurality of gatekeepers are collected to form a multi-zone, and other gatekeepers for controlling the multi-zone may exist.
The gatekeeper has various kinds of principal functions such as an address translation function, a call admission function, a bandwidth control function, a call control function, and a maintenance function. The address translation function translates an alias name or a destination number into a network address (i.e., an IP address). The call admission function means a function by a RAS (Registration/Admission/Status) protocol generically naming protocols related to a gatekeeper in the H.323 standards. The bandwidth control function distributes a limited bandwidth of a network into a plurality of endpoints, and performs a blocking function by checking whether the bandwidth reaches a threshold value or not. The call control function makes a call connection/disconnection between endpoints through the medium of a gatekeeper. The maintenance function means a supplementary function such as accounting or statistics.
One of the basic signaling protocols of the gatekeeper is the RAS. The RAS is a protocol for implementing a basic interface between endpoints (e.g., a terminal, gateway, and MCU, etc.) and a gatekeeper. In the RAS, the gatekeeper is a server, and the endpoints are clients. Namely, the RAS is a basic protocol necessary for the gatekeeper functioning as the server to manage/control/monitor the endpoints functioning as clients, in such a way that the gatekeeper can reflect the RAS results in its own operation and control procedure. The registration mode in the RAS means that the endpoint (client) registers its own presence to the gatekeeper (server).
An admission mode in the RAS determines whether the endpoint follows the rules of H.323 and a corresponding zone in the gatekeeper, and permits access to a VoIP network upon receiving the result signal. Herein, the rule of H.323 determines whether an alias name being a registration ID (Identification) of the endpoint is equal to that of another endpoint. The rule of the corresponding zone determines whether a corresponding endpoint is registered to the gatekeeper.
In the status mode of the RAS, the endpoint periodically informs the gatekeeper of its own information and current status in such a way that the gatekeeper acquires information needed to operate/control the endpoint, thereby making a periodic link test between a server and a client.
As stated above, a communication interface between an IP terminal (i.e., IP-phone) and a gatekeeper in the VoIP system or the IP telephony system is performed according to the RAS protocol functioning as a H.323 protocol being one of ITU-T standards. However, the communication interface between the IP phone and the gatekeeper according to the RAS protocol has the following problems, resulting in user's inconvenience in operation.
Firstly, a user must manually input initialization information (e.g., a server IP address, and H.323 ID, etc.) in initializing the IP phone and the gatekeeper.
Secondly, a signal mismatch occurs in performing a link restart between the IP phone and the gatekeeper, resulting in user's inconvenience in operation.